This invention relates to fuse pullers and, in particular, to a device for removal of a blade-type fuse like that disclosed in U.S. Pat. No. 3,909,767. This fuse, developed in the 1970's and now used in all U.S. made automobiles, has a head portion overhanging the opposite sides of a lower housing portion from which depends blade terminals which are extendable into pressure clip terminals of a mounting block having relatively small recesses for receiving the fuses protecting various electrical circuits of the automobiles involved.
While the overhanging head portion of the fuse housings can be grasped by the user's finger to withdraw the fuses from the recesses of the fuse block, it has been thought more convenient to use fuse pulling devices for this purpose. Two types of fuse pulling devices have heretofore been utilized for this purpose. One form has a scissors-like design including a pair of initially widely spaced apart jaw sections which fit over the head portion of the fuse. The user squeezes finger-squeezable end portions of the device to cause the jaw sections thereof to grip the lower portion of the housing immediately below the head portion thereof, so that withdrawing the fuse puller while maintaining pressure on the finger-squeezable portions the fuse can be readily removed from the mounting block. This device, because of its scissor-like construction, could not be readily molded as a single piece and so the cost of manufacturing such a fuse puller was more substantial than desired. Also, the construction of a scissor-type fuse puller makes it difficult if not practically impossible to add to the fuse puller an indicator unit which could be used to indicate the continuity or discontinuity of the fuse involved, as in the case of some prior art fuse puller devices for cylindrical fuses which were also designed to act as fuse condition indicators.
Another type of fuse puller device heretofore developed has a clothes-pin like construction; that is, it includes a pair of confronting jaw sections which are initially spaced apart relatively closely, so that they can grip the lower portion of the fuse housing below the overhanging head portion thereof in its normal condition. This fuse puller device has confronting finger squeezable sections which when squeezed separate the jaw sections thereof to permit it to be placed over the head portion of the fuse housing or to remove it from the fuse housing after the fuse had been removed from the mounting block. This fuse puller device is a one piece synthetic molded device, which therefore could be made at a much lower manufacturing cost than the scissor-type fuse puller device described. However, this type of device suffers from the disadvantage heretofore thought inherent in such a device in that it was thought necessary to design it to require a substantial squeezing force to open the jaw section because, otherwise, the grasping force of the user in the process of pulling the device away from the mounting block could readily accidentially open the jaw sections of the fuse puller device so that the fuse would be dropped in the process of removing the same from a mounting block. Another disadvantage of this fuse puller device is that it was not readily adaptable to be combined with an indicator unit for indicating fuse continuity.
As previously indicated, there has been heretofore developed fuse puller and fuse condition indicating devices useable only with a conventional cylindrical-type fuse which has metal terminals at the ends of a cylindrical glass envelope. One of these devices has clamping jaws which engage the terminals of the fuse and also act as terminals for an indicating circuit including an indicating lamp, so that when the fuse puller device is applied to the terminals of the fuse if the fuse has continuity shown by the de-energization of the indicating lamp shunting the fuse, the fuse is left in place. However, if upon application of the combination fuse puller and indicating device the lamp is energized indicating no fuse continuity, the user withdraws the defective fuse from the fuse mounting block by pulling the fuse gripping puller device away from the fuse mounting block. In such a device, there is no problem of centering the fuse puller device so that it makes proper electrical contact with the fuse terminals when it is applied to the fuse, since the gripping jaws thereof also act as the terminals for the indicator. To our knowledge, there has not been heretofore proposed a combination fuse puller and fuse condition indicating device useable with the blade-type fuse described, where fuse continuity test terminals are commonly exposed on the outer face of the head portion of the fuse, so that the gripping jaws of the fuse puller device which are to underlie this head portion cannot also act as terminals for an indicating lamp circuit.
It is, accordingly, one of the objects of the present invention to provide a fuse puller device useable with the blade-type fuse described and of a clothes pin-type construction so that it can be more readily made as a one piece synthetic plastic molded product, but wherein it does not have the disadvantages of the previously described clothes pin-type fuse puller device, namely the difficulty of opening the fuse puller and/or incorporating a fuse condition indicator unit in connection therewith.
Another object of the invention is to provide a fuse puller device for the blade-type fuse described, whether it be of the clothes pin-type or the scissors-type, which is adapted to be used with a fuse condition indicator unit for indicating continuity of the fuse and which can be readily centered on the fuse so that the indicator unit terminals which are separate from the jaws thereof will be aligned with the fuse continuity test terminals on the outer face of the fuse housing.
A still further object of the invention is to provide a fuse puller device of the clothes pin-type which is designed in such a fashion that the finger squeezable portions thereof used to open the fuse puller can be opened with a much smaller force than that required to open the prior art clothes pin-type fuse puller device described, but without the danger that the device would be opened in the process of pulling the fuse puller device in a direction to remove a fuse from a mounting block recess.